1. Field of the Invention
The present invention relates to the field of data processing systems. Specifically, the present invention relates to a method and apparatus for synchronizing information between a portable computer system and a computer system having shared scheduling information stored thereon.
2. Related Art
As the components required to build a computer system have reduced in size, new categories of computer systems have emerged. One of the new categories of computer systems is the “palmtop” computer system. A palmtop computer system is a computer that is small enough to be held in the hand of a user and can be “palm-sized.” Most palmtop computer systems are used to implement various Personal Information Management (PIM) applications such as an address book, a daily organizer and electronic notepads, to name a few.
Since palmtop computer systems are very small, full-sized keyboards are generally not efficient input devices. Palmtop computers using keyboards have keyboard devices that are so small that a user cannot touch-type. Furthermore, to use a keyboard device, a user must either place the palmtop computer system down onto a flat surface, so the user can type with both hands, or the user holds the palmtop computer system with two hands and types with thumbs only.
Instead of a keyboard device, some palmtop computers utilize a touch screen and display an image of a small keyboard thereon. When a particular button is pressed or tapped, a small keyboard image is displayed on the display screen. The user then interacts with the on-screen small keyboard image to enter characters, usually one character at a time. To interact with the displayed keyboard image (e.g., “virtual keyboard”), the user taps the screen location of a character with a pen. That corresponding character is then recognized and added to a data entry field, also displayed on the screen. However, for experienced users, the virtual keyboard input system can be a tedious input process.
Instead of using a keyboard device or a displayed keyboard, many palmtop computers employ a pen and a digitizer pad as an input system. The pen and digitizer pad combination works well for palmtop computers because the arrangement allows a user to hold the palmtop computer system in one hand while writing with the pen onto the digitizer pad with the other hand. Most of these pen-based palmtop computer systems provide some type of handwriting recognition system whereby the user can write words and letters on the digitizer pad with a stylus.
In addition to using keyboards, virtual keyboards and the digitizer, it has also proven convenient to exchange data between a computer system and a palmtop computer using a communication interface, such as a serial or parallel input port. A number of programs today transfer data between palmtops and personal computer systems (PCs), but they are currently limited in functionality. For instance, some programs transfer all the information from the palmtop to the PC without regard for the prior content on the PC. These programs assume that changes to that particular data are only made on the palmtop, and that the changes made on the palmtop take precedence over any changes made on the PC. As a result, any independent updates made directly on the PC will be lost.
Other methods track changes, e.g., using “flags,” to facilitate synchronization. These methods create update “flags” in each record that has changed, both on the palmtop and the PC. Corresponding files on the palmtop and the PC are then compared, and if one or more flags are set in a file, the file is recognized as having changed. If both the palmtop and PC files have changed, the flags are used to determine which records need to be updated in the other file. The databases of most existing programs, however, do not contain such flags since the databases of most existing programs were not designed to be synchronized. Also, there is no provision in these methods for sharing the scheduling information of or for multiple users with a palmtop computer.
Some programs attempt to synchronize the data on the PC with the palmtop by comparing the information in each application and prompting the user for answers to determine which data to overwrite. For example, U.S. Pat. No. 5,392,390 describes a method for reconciling information between two calendar database files by interrogating the user about which file to update when a difficult case arises. Although these types of programs provide an advantage over programs that assume only one database has changed since they do not indiscriminately overwrite data, they are cumbersome and time consuming. Using these methods, users may have to spend an inordinate amount of time answering questions whenever they attempt to synchronize information between their palmtops and their PCs. Furthermore, none of these systems provide for the management of shared calendar information (of multiple users) with a palmtop computer system.
Other systems, such as those described in U.S. Pat. No. 5,727,202, U.S. Pat. No. 5,832,489 and U.S. Pat. No. 5,884,323 allow data synchronization between a portable computer system and a desktop computer system for the exchange and updating of data. However, like the above described systems, there is no provision for management of a shared data file of calendar information from or for multiple users.